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Full text of "Alaskan glacier studies of the National Geographic Society in the Yakutat Bay, Prince William Sound and lower Copper River regions"

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60                                   ALASKAN GLACIER STUDIES
condition is based upon these observations.   The glacier was seen only from the east side of Yakutat Bay in 1910.
Description by Russell Lucia Glacier was inactive in 1890, for Russell described it during the first part of July, 1890, as "covered from side with angular masses of sandstone and shale . . . while further up the valley the debris on the surface of the ice disappeared, and all above was a winter landscape. The brown desolate debris fields extended far southward, and covered the expanded ice foot in which the glacier terminates. Most curious of all was the fact that the moraines on the lower border of the glacier were concealed from view by a dense covering of vegetation, and in places were covered with forests of spruce trees." He also described the nunatak on the west side of the glacier and the outwash plain at its base.
Continued Inactivity in 1905 and 1906. Lucia Glacier seems not to have changed significantly between 1890 and 1905; and between 1905 and 1906, there was no notable difference, except a possible increase in crevassing up the valley to which reference will be made later. In 1905 it was impossible to clearly detect the boundary between Lucia and Atrevida ice tongues, the two lobes of this piedmont glacier; though for a part of the distance a line of alder growth, forming an oasis in a broad waste of ablation moraine, marked the site of the interlobate area of greatest stagnation. Above this the two glaciers were separated by the gravels of Terrace Point, and near the outer border of the piedmont glacier a stream emerged and formed a valley, apparently in line with the boundary between the two lobes; but for some distance above this valley the twa lobes so coalesced that the boundary between them was indistinguishable. In 1906, however, the advance and crevassing of Atrevida Glacier, which pushed westward into* the still stagnant Lucia lobe and destroyed the interlobate strip of alder, brought out sharply the area occupied by each lobe (Pis. XXVI and XXVH). The Atrevida lobe was everywhere broken, with clear ice showing along the boundary between the two-lobes, while the Lucia was unchanged—a broad, undulating waste of ablation moraine which, from a distance, bore little resemblance to a glacier.
One of the most interesting features of the Lucia Glacier was its ablation moraine; it seemed stagnant near its terminus and wasting in its valley and was the best illustration of this type in the Yakutat Bay region. For over 7 miles, from its terminus to a point well up the mountain valley, the glacier surface was obscured by ablation moraine (PI. XVII, A), and throughout fully nine-tenths of the area no ice could be seen from a distance. The ablation moraine extended well up the valley portion of the glacier, to a point at least a mile above Floral Pass, becoming rapidly thinner, with more ice showing up the valley, and finally giving place to bands of medial and lateral moraine. Opposite and below Terrace Point the moraine increased in proportion and ice appeared only in small bands, or in depressions holding lakelets, at least a score of which dotted the moraine-covered portion of the glacier. The surface of this desert waste of ablation moraine was nowhere notably crevassed, and travel over the surface was possible in all directions, the only difficulty being the extreme irregularity of the surface due to differential melting, and the occasional slippery slopes where the moraine veneer was thin. There were numerous moulins of large size, and morainic d6bris was-being carried into these by the drainage. This was the only escape for the concentrated morainic debris, for there were no crevasses of any considerable depth in this slowly moving glacier.